Hey All,

I have been searching and searching for an answer to this issue I am having and can't seem to locate as of yet.

2002 cbr f4i

My bike recently started popping and backfiring when down shifting. I also noticed the exhaust sounded much deeper and louder. Smelled of fuel very rich. This was not to long after replacing CCT to a manual one. Recently while riding the bike started to stall when coming to a stop at a stop light. As of today the bike won't turn over at all.

Things I have checked so far.

- Checked injectors to ensure all were seated properly. Replaced gaskets on injectors. This corrected the back firing issue the first time for a while.
- Checked fuel pressure regulator. Disconnected the vac line turned key over fuel pump engaged, no fuel was coming out of the vac line. Appears fine.
- Thought maybe stator. Charged bike over night, took it for a ride first thing and still same results. Stalled at end of street with battery fully charged.
- Ensured all battery connections are good tight.
- Checked fuses under seat, all look fine.
- When pushing start button one of boxes under seat clicks so seems to be getting voltage.

This definitely seems to be a air fuel ratio issue however I'm kinda stumped at the moment.

Does anyone have any insight? Spark plugs changed within last 5000-10,000km. I don't think it's the plugs but at this point i'm at a loss.

Any insight would be greatly appreciated guys.

Thank you in advance.

 

The plugs are probably fouled with fuel, if its running that rich. Definitely worth the time to pull them and take a look.

If the fpr is good, and it's still dumping fuel, the next step would be to see if an injector is leaking.

 

I am not 100% if the FPR is good. The bike doesn't seem to be getting fuel now as it won't start. Turning over fine just won't actually fire.

Did I test the FPR correct? pull vac line, turn ignition on... fuel pump turns on... if it doesn't drip it's not broke correct?

I'll grab some new plugs and see if that fixes it and report back.

Thank you for the direction, i'll report back once I see if it corrects the issue.

 

When the FPR goes bad, the diaphragm inside tears and fuel gets into the vacuum line, thus putting extra fuel through the intake. But only if there is pressure from the pump.

Don't just grab new plugs. Take them out and look at them. They will tell you what is going on inside the cylinder.

You need to find out if it's getting fuel and spark.

 

Check fuel pressure. Perhaps the pump is going out. Also check for spark as mentioned. A bad coil would make it run crappy and smell rich.

 

Sorry for the slow response guys. Work has kept me busy so I have to squeeze this in when I can.

I checked fuel pump, it's def pumping strong no issues.

Plugs were black. Replaced them. Bike is running again.

I still have an issue of some sort. When I'm gearing down instead of a "popping" noise it sounds like a deep "bow" with the odd "pop" if that makes sense. This was happening previously. I don't want to ride it to much because i'm sure that's what fouled the plugs in the first place.

I think i'm getting closer but i'm really starting to scratch my head.

Thoughts?

How would I check the coil?

 

If it's running, the coils are probably okay. You have 4 of them and they either work or they don't.

What did the old plugs look like?
It's a little late now, but it's helpful to keep them order so you know which cylinder is not firing right.

 

Old plugs are fouled really bad. Black.

I called the shop today, they think its timing it's going in on Tuesday to get timing adjusted or to shed some light hopefully.

I will let you know what it turns up to be.

 

Timing? There is no ignition timing adjustment. The only thing to "time" is the cam chain+gears, and those don't go out without the chain jumping teeth. Timing is not the issue.

 

I was originally just going by what they told me a the shop.

I took it in today, turns out the bottom side of the vac line that runs along side the throttle body rubbed a big hole in it causing issues with map sensor.

$100 bucks for them to look at and fix it worth every penny after the amount of times I had it apart.

Thanks again for your help everyone. Happy riding and I can't wait to get back out again!

Cheers!